Oxidative Stress Induces Mitochondrial Compromise in CD4 T Cells From Chronically HCV-Infected Individuals

Abstract

We have previously shown that chronic Hepatitis C virus (HCV) infection can induce DNA damage and immune dysfunctions with excessive oxidative stress in T cells. Furthermore, evidence suggests that HCV contributes to increased susceptibility to metabolic disorders. However, the underlying mechanisms by which HCV infection impairs cellular metabolism in CD4 T cells remain unclear. In this study, we evaluated mitochondrial mass and intracellular and mitochondrial reactive oxygen species (ROS) production by flow cytometry, mitochondrial DNA (mtDNA) content by real-time qPCR, cellular respiration by seahorse analyzer, and dysregulated mitochondrial-localized proteins by Liquid Chromatography-Mass Spectrometry (LC-MS) in CD4 T cells from chronic HCV-infected individuals and health subjects. Mitochondrial mass was decreased while intracellular and mitochondrial ROS were increased, expressions of master mitochondrial regulators peroxisome proliferator-activated receptor 1 alpha (PGC-1α) and mitochondrial transcription factor A (mtTFA) were down-regulated, and oxidative stress was increased while mitochondrial DNA copy numbers were reduced. Importantly, CRISPR/Cas9-mediated knockdown of mtTFA impaired cellular respiration and reduced mtDNA copy number. Furthermore, proteins responsible for mediating oxidative stress, apoptosis, and mtDNA maintenance were significantly altered in HCV-CD4 T cells. These results indicate that mitochondrial functions are compromised in HCV-CD4 T cells, likely via the deregulation of several mitochondrial regulatory proteins.

Mitochondrial topoisomerase 1 inhibition induces topological DNA damage and T cell dysfunction in patients with chronic viral infection

“…We have previously reported that chronic viral infection induces T cell aging and immune senescence due to accelerated telomeric DNA damage and mitochondrial dysfunction ( Yao and Moorman, 2013 ; Shi et al., 2014 ; Li et al., 2015 ; Zhou et al., 2016 ; Nguyen et al., 2018 ; Zhao et al., 2018 ; Cao et al., 2019 ; Ji et al., 2019 ; Zhao et al., 2019 ; Dang, 2020 ; Khanal et al., 2020 ; Schank et al., 2020 ; Khanal et al., 2021 ; Nguyen L. N. et al., 2021 ; Nguyen L. N. N. T. et al., 2021 ; Schank et al., 2021 ; Schank et al., 2021 ; Wang et al., 2021 ; Zhao et al., 2021 ; Cao et al., 2022 ). Given the crucial role of DNA topology in maintaining mitochondrial integrity and cell function and viability ( Champoux, 2001 ; Wang, 2002 ; Vos et al., 2011 ), here we sought to determine the levels of Top1 protein in the mitochondria of CD4 T cells from chronically HCV- or HIV-infected patients.…”

“…T cells play a critical role in controlling viral infections; however, the molecular mechanisms that dampen their responses during viral infections remain incompletely understood. We have recently reported that chronic viral (HCV, HIV) infection can cause T cell aging, as evidenced by the increases in the aging markers, telomeric and mitochondrial DNA damage, and mitochondrial dysfunction ( Yao and Moorman, 2013 ; Shi et al., 2014 ; Li et al., 2015 ; Zhou et al., 2016 ; Nguyen et al., 2018 ; Zhao et al., 2018 ; Cao et al., 2019 ; Ji et al., 2019 ; Zhao et al., 2019 ; Dang, 2020 ; Khanal et al., 2020 ; Schank et al., 2020 ; Khanal et al., 2021 ; Nguyen L. N. et al., 2021 ; Nguyen L. N. N. T. et al., 2021 ; Schank et al., 2021 ; Schank et al., 2021 ; Wang et al., 2021 ; Zhao et al., 2021 ; Cao et al., 2022 ). Mitochondria are important cellular organelles responsible for energy production and oxidative metabolism and are a major source of reactive oxygen species (ROS).…”

“…Mitochondria are important cellular organelles responsible for energy production and oxidative metabolism and are a major source of reactive oxygen species (ROS). We have examined mitochondrial dysregulation in CD4 T cells during HCV or HIV infections and discovered that oxidative stress, caused by excess ROS production, induces mitochondrial injury and accelerates telomere erosion - a dual effect that can promote the T cell aging process and, eventually, cell death ( Schank et al., 2020 ; Schank et al., 2021 ; Schank et al., 2021 ; Wang et al., 2021 ; Zhao et al., 2021 ). Thus, further investigation into how the mitochondrial machineries, especially mitochondrial DNA (mtDNA), are disrupted during chronic viral infections may provide new information regarding the mechanisms of CD4 T cell dysfunction and viral persistence ( Schank et al., 2021 ; Zhao et al., 2021 ).…”

The Role of Metabolic Dysfunction in T-Cell Exhaustion During Chronic Viral Infection

“…Inhibition of CPT1A can reduce mitochondrial respiration by about 50% in early exhausted T cells, suggesting early exhausted T cells switch the energy pathway to FAO when glycolysis is restricted ( 27 , 68 ). In addition, enhanced expression of PD-1 in exhausted T cells can also promote mitochondrial depolarization by reducing the transcriptional expression of peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α), a key transcriptional regulator involved in the regulation of energy generation and mitochondrial biogenesis genes, and mitochondrial transcription factor A (mtTFA) ( 68 , 73 ). Overexpression of PGC1α can promote metabolic fitness by enhanced glycolysis and mitochondrial respiration, and reduce depolarized mitochondria the in early exhausted T cells ( 17 , 27 , 68 , 73 ).…”

“…In addition, enhanced expression of PD-1 in exhausted T cells can also promote mitochondrial depolarization by reducing the transcriptional expression of peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α), a key transcriptional regulator involved in the regulation of energy generation and mitochondrial biogenesis genes, and mitochondrial transcription factor A (mtTFA) ( 68 , 73 ). Overexpression of PGC1α can promote metabolic fitness by enhanced glycolysis and mitochondrial respiration, and reduce depolarized mitochondria the in early exhausted T cells ( 17 , 27 , 68 , 73 ). Recent studies also revealed that continuous TCR stimulation under hypoxia promoted expression of Blimp-1, another transcriptional repressor of PGC1α, which induced the exhaustion of CD8 + T cells by repressing PGC1α-dependent mitochondrial reprogramming ( 74 , 75 ).…”